delta-syncrepl would probably be your best bet. Normal syncrepl has
much larger bandwidth requirements than slurpd or delta-syncrepl.

That seems to work very nicely (at least with one consumer). I'm unsure
as to the necessity of syncprov-sessionlog parameter on the provider. Is
it still required when using delta-syncrepl?

I don't believe so. I certainly don't use it. I believe its purpose is
replaced by the accesslog backend, essentially. ;)

I'm thinking of deploying the exact same configuration to all consumer
slapds. May the replica-id (rid=) in the syncrepl stanza be the same for
all consumers or must it be unique accross all consumers?